Seminar - Professor Colombo Bolognesi

Tuesday, July 4, 2017 2:00 pm - 2:00 pm EDT (GMT -04:00)


Professor Colombo Bolognesi, ETH-Zurich


Terahertz InP/GaAsSb Double Heterojunction Bipolar Transistors


The presentation will relate the development of InP/GaAsSb–based "THz Transistors" from the 1997 inception of a raw concept to the present transistors, showing power gain cutoff frequencies exceeding 1 THz, as determined by conventional de-embedding techniques.

It is not widely appreciated that InP/GaAsSb double heterojunction bipolar transistors (DHBTs) pioneered by the Professor Bolognesi`s group in Canada are at the heart of modern high-speed test and measurement equipment such as vector network analyzers (VNAs), digital oscilloscopes and bit error rate testers (BERT) commercialized by Keysight Technologies thanks to a collaboration with Nick Moll, who coincidentally was the son of John Moll (of "Ebers-Moll model" fame).

By year 2000, devices from the Professor Bolognesi`s lab in SFU had already exceeded all expectations by becoming the fastest bipolar transistors ever made at the time, in any material system, with 300 GHz cutoff frequencies breakdown voltages in excess of 6V. A basic fabrication process was transferred to the then Agilent Research Laboratories in Palo Alto (CA) in year 2000 which itself transferred an industrialized version to the Santa Rosa (CA) plant where the technology went into production in 2004. This is an unusually swift ramp up from laboratory to production for a semiconductor device, considering that it took 10 years for HP/Agilent to develop its GaAs process at a time when many organizations were active with GaAs.

The talk will discuss the features of InP/GaAsSb DHBTs in contrast to the more common InP/GaInAs devices from a band engineering point of view and relate the path further developments are likely to take.


Colombo R. Bolognesi was born in Montreal, Canada. He earned the B.Eng. from McGill University (Montréal), the M.Eng. from Carleton University, and the Ph.D. from the University of California, Santa Barbara (UCSB) in 1993, all in Electrical Engineering. His doctoral work was performed in Herbert Kroemer (Nobel Laureate 2000), and dealt with the MBE growth, fabrication and physics of InAs/AlSb HEMTs.

Invited by John R. Long.